Microbial Bioinsecticide

Mode of Action
• The parasporal crystal is not the active form of the insecticide,
rather, it is a protoxin, a precursor of the active toxin.
• When the parasporal crystal is ingested by a target insect, the
protoxin is activated within its gut by the combination of alkaline
pH (7.5-8.0->>) and specific digestive proteases, which converts
the protoxin into an active toxin (Mol Mass ~68 kDa.)
• In its active form, the toxic protein inserts itself into the
membrane of the gut epithelial cells of the insect and create an
ion channel through which there is believed to be an exessive
loss of cellular ATP.
• Cellular metabolism ceases, the insect stops feeding, becomes
dehydrated, and eventually dies. Because conversion of protoxin
to active toxin requires : alkaline pH and specific proteases.